The OSM maps for South Africa do not allow you to enter the city name before deciding that you are entering the city of the map's choice - typically if you try to enter Johannesburg (a major metropolis in South Africa), it immediately gives you the choice of 2 incredibly obscure little villages immediately after you enter the "J". Same problem with all the other major names. Map is basically useless as a means of navigation to a known address This is true of the December version as well as the latest version d/l today.

Just in case you don't know what Frederik means: OSM is actually a database of geographical information. This information can be used by anyone to make a map. So in order to answer your question, it is important to know where you retrieved the map and which application you are using. E.g. There are maps for Garmin devices (from different sources, all using OSM-data), and many different smartphone application that use OSM data.
And, of course there are maps on osm.org, but I doubt you are referring to that one.